my servos work in a bit lower voltage range...are you not concerned with voltage overload on the servos, with the LiFe battery having 6,6 Volts rated voltage? (I had a few almost-mortal, in-flight problems with electronics, especially the servos and sometimes the battery, that I am a bit paranoic)

Will use a simple step down voltage regulator these are only 10mm wide andvery thin, can be put under the RX to drop it to a safe 5v. Using a 6.6v LiFe battery in the Nano III has been great as they hold their charge for weeks without voltage loss. I paid .99 cents each.

You may want to try this 400mAh NiMH I use in my small birds...gives you confidence that 5 or more 10 minutes flights will still not leave you without juice in the battery in the field, or worse, mid-air...